Various solid catalyst components comprising magnesium, titanium, halogen and an electron donor as essential components, have been proposed for catalyst components for olefin polymerization. It has been known that these solid catalyst components have high activity in olefin polymerization and alpha-olefins produced by using them have high stereospecificity. In particular, it has also been known that when an aromatic ester represented by phthalates is used as an electron donor to produce the solid catalyst components, they exhibit excellent catalyst properties.
However, compounds containing an aromatic ring have been disliked from the point of view of safety and hygiene.
On the other hand, for electron donors not containing an aromatic ring (non-aromatic electron donors), malonic ester derivatives are reported. For example, Japanese Patent Kokai H8(1996)-157521 shows non-aromatic compounds of the general formula (I)
wherein R1 and R2 are independently a C1-10 straight or branched hydrocarbon group, R3 and R4 are independently a C3-20 saturated hydrocarbon or cyclic saturated hydrocarbon group containing at least one secondary or tertiary carbon atom, and n is 1.
However, the publication does not show a compound which is the same as the electron donors of the present invention.
The applicant of the present invention discloses compounds of the formula (I) wherein R1 and R2 are a C1-20 straight or branched hydrocarbon group, R3 and R4 are a methyl group and n is an integer of 1 to 10, as an non-aromatic electron donor, in Japanese Patent Kokai H11(1999)-60625.
The publication disclose 14 malonic esters, two compounds of which are the same as electron donors of the present invention.
However, catalyst systems using the two compounds were not evaluated.
Further, the applicant discloses various malonic esters containing compounds of the formula (I) wherein R1 and R2 are a C1-20 straight or branched hydrocarbon group, R3 is hydrogen, R4 is a C3-20 aliphatic cyclic hydrocarbon group and n is an integer of 1 to 10, as an non-aromatic electron donor, in Japanese Patent Kokai H11(1999)-199628.
However, the publication does not show a compound which is the same as the electron donors of the present invention.
As stated above, although some non-aromatic electron donors have been already known, an electron donor is demanded which can form a catalyst with higher stereospecificity and activity.
An object of the present invention is thus to provide a solid catalyst component and a catalyst for olefin polymerization which maintain high stereospecificity with a high activity but do not use an electron donor having problems of safety and hygiene, and methods for producing them.